.bears {
    position: absolute;
    bottom: 0;
    width: 200px;
    height: 100px;
    background: url(../img/bear.png) no-repeat;
    /* 我们元素可以添加多个动画， 用逗号分隔 */
    animation: bear .4s steps(8) infinite, move 3s forwards;
}

.bg {
    left: 0;
    bottom: 0;
    width: 100%;
    height: 250px;
    position: absolute;
    background: url(../img/bg1.png) no-repeat;
    z-index: -1;
    animation: bgmove 5s infinite;
}

.bg1 {
    left: 0;
    bottom: 0;
    width: 100%;
    height: 350px;
    opacity: 0.8;
    overflow: hidden;
    position: absolute;
    background: url(../img/bg2.png) no-repeat;
    z-index: -1;
    animation: bgmove 5s infinite;
}

@keyframes bear {
    0% {
        background-position: 0 0;
    }
    100% {
        background-position: -1600px 0;
    }
}

@keyframes move {
    0% {
        left: 0;
    }
    100% {
        left: 50%;
        /* margin-left: -100px; */
        transform: translateX(-50%);
    }
}